Knee disorders are a major source of disability and early departure from work but there is limited knowledge about the risk of knee disorders related to work. Most studies finding associations with work have relied on job titles or relatively simple questionnaire surveys for exposure assessment and characterized exposure crudely, without information on level or type of biomechanical risk factors. As a result, little is known about the association of knee disorders with compressive force or torque on the knee joint resulting from varying intensities and durations of exposures to awkward sustained postures, squatting, kneeling, weight lifted, etc. Recent advances in field observation methods and questionnaire-based exposure assessment in occupational epidemiology permit us to improve upon this qualitative risk characterization by providing better specification of types of ergonomic risk factors along with semi-quantitative estimates of exposure intensity for these. A working population of union carpenters will be targeted because they have a range of types and intensity of biomechanical risks for knee disorders. The proposed study is designed with a focus on the risk of osteoarthritis and other chronic knee conditions associated with chronic biomechanical exposures to the lower limb. The specific objectives are to develop and evaluate methods to: 1) identify and characterize incident cases of knee disorders using medical insurance records available from the Carpenters' Combined Benefits Fund of Massachusetts and the Carpenters' Health and Welfare Trust Fund of St. Louis; and 2) assess a diverse range of exposures occurring in carpenters' jobs through observational analyses in the field. Including the databases from both states doubles the study population and permits inclusion of the full range of carpenter tasks as well as regional comparisons of disorders and exposures. The outcomes from this study will be new knowledge about biomechanical exposures in these jobs that can be directly applied to preventing known risk circumstances (e.g., tasks resulting in unacceptable torque), as well as methods that can be applied in a subsequent case-control investigation designed to provide quantitative data on the associations between osteoarthritis and other knee disorders and occupational exposures experienced by carpenters. [unreadable] [unreadable] [unreadable]